Generated code import ordering is random

[dbushong]

The list of imports are collected in a set() (I believe) and so their ordering is not stable. We should either sort them when emitting code or use a stable method of making them unique (e.g. a dict()). Having the code change every time it is regenerated makes for undesirable diff churn when generated code is checked into a repo and regularly regenerated as part of automated tooling.

[sbrunner]

Personally, I'm not concerned because I do an isort on the generate code via a pre-commit :-)